Meaning & Basic Property of Proportion

A proportion is an equation of two equal ratios; the product of the means equals the product of the extremes

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About This Practice

A proportion is an equation stating that two ratios are equal, like 3 : 4 = 6 : 8. In a proportion a : b = c : d, the product of the means equals the product of the extremes: a × d = b × c. This basic property is a fast test for whether two ratios form a proportion — tap Yes or No first, then watch the crossing arcs compute both products and verify.

Get two random ratios, decide whether they form a proportion, then watch the cross-multiply arcs reveal the answer: the products of the extremes (a×d) and of the means (b×c) are equal exactly when the ratios form a proportion. Both proportional and non-proportional cases appear.

MediumEstimated Time: 12minproportionmeansextremescross multiplybasic property

How to Play

  1. Look at the two ratios: are their values equal?
  2. Tap Yes or No to make your judgment.
  3. Watch the crossing arcs: the extremes product (1st × 4th) and the means product (2nd × 3rd).
  4. Compare the products: equal means it is a proportion, different means it is not.
  5. Take a new problem and test means = extremes again.

Learning Objectives

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